Combustion equipment with a flameless combustion chamber, applications of such equipment, and power generation or cogeneration equipment including such equipment.

Abstract

A combustion device (100) for power generation or cogeneration equipment is disclosed, characterized in that: a combustion tube (5) is closed at its other end, referred to as the rear end, by a bottom (12) which is fixed to the combustion tube (5); and a means for discharging combustion gases includes at least one opening (9) arranged at the front end of the combustion tube (5), the opening (9) being defined by a tubular longitudinal wall and a closed wall (14) of the combustion tube (5) to allow combustion gases to flow between the longitudinal wall and the outer tube (26).

Description

Technical Field

[0001] This invention relates to a combustion device and a power generation or cogeneration equipment including said device. A combustion device refers to a device comprising one or more combustion chambers or sub-chambers.

[0002] In particular, the present invention relates to a combustion system, for example, using gaseous fuel and operating in a "flameless" state, which is connected to a regenerator and incorporated into a micro gas turbine that operates using natural gas as feedstock. Background Technology

[0003] It is known that the supply to the turbine is in "flameless" oxidation (or FLOX). ® The combustion chamber operating under these conditions can achieve extremely low NOx emissions, for example, < 10 ppm.

[0004] Known as "MILD combustion" (MILD is...) Moderate or severe hypoxia dilution Flameless combustion (MILD) is a combustion mode that provides high combustion efficiency with very low pollutant emissions, even under conditions of highly preheated air. In addition to the improved energy efficiency associated with heat recovery processes, MILD combustion also provides a uniform combustion environment due to the high degree of exhaust gas recirculation. This manifests itself in a localized reduction in O2 levels compared to conventional combustion with a visible flame, resulting in a distributed reaction zone and a lower operating temperature. The reduced temperature level and uniform reaction environment have a positive impact on significantly reduced pollutant (NOx, soot) formation and material resistance, as there is no steep temperature gradient. MILD combustion allows for a great deal of flexibility in fuel types, making it an ideal technology for fuels such as low-calorific-value fuels, high-calorific-value industrial waste, hydrogen-based fuels, liquid fuels (e.g., kerosene, petroleum, diesel, heavy oil), and solid fuels.

[0005] From the perspective of chemical turbulent interactions, MILD combustion is characterized by a high degree of coupling between the chemical reaction time scale and fluid transport phenomena. In MILD combustion, the Damköhler number Da (the ratio between the fluid transport rate and the chemical reaction time scale) is approximately one, indicating that the chemical reaction time is not negligible compared to the time scale governing fluid transport.

[0006] In conventional combustion, the overall process is controlled by heat and mass transfer, resulting in a well-defined reaction zone with steep temperature and species gradients and a Da value greater than one. In flameless combustion, the recirculation of exhaust gases (also known as combustion gases) thus causes a more uniform distribution of temperature and species.

[0007] Typically, flameless combustion is very stable and quiet, and therefore can be used in gas turbine applications where conventional operation may lead to thermoacoustic instability (“humming”) and significant stress.

[0008] Flameless combustor designs for (micro) gas turbine applications are known. In micro gas turbine applications, the temperature of the exhaust gas leaving the combustor is limited by the tolerances of the materials used to manufacture the turbine, typically ranging from 800°C to 1050°C, and particularly from 950°C to 1050°C. This necessitates the use of a very large excess of air compared to the stoichiometric amount of air required for fuel combustion.

[0009] In the applications of this invention, the λ ratio (air mass flow rate / stoichiometric air mass flow rate or 1 + excess air) can be very high (significantly greater than 1) so that the temperature of the gas can be reduced to a temperature compatible with the turbine inlet. The result of this is the presence of a large amount of O2 available for combustion, which seems to contradict the ideal conditions for implementing flameless combustion, which depend primarily on the dilution of O2 in the mixture.

[0010] Furthermore, another condition conducive to the initiation of flameless combustion involves preheating the oxidizing air to a sufficiently high temperature to ensure the mixture is readily ignited. Using a regenerator present in the gas turbine cycle, along with regeneration, facilitates this function.

[0011] Numerous combustor designs capable of operating in a flameless state have been proposed. For example, the gas turbine combustor described in document WO2003 / 091626 can be mentioned. This chamber is configured with open internal guide pipes at both ends, allowing a large proportion of the combustion gases to be recirculated within the chamber, while the remaining proportion is discharged downstream. This recirculation enables the maintenance of a flameless oxidation state within the chamber. These known solutions undeniably enable the achievement of low NOx levels, but they are not designed to achieve low CO levels.

[0012] Document CN 105299692 A discloses a combustion chamber device for large-area exhaust gas disinfection and epidemic prevention. The combustion chamber device includes a flame tube, a diffuser section, an air distribution plate, a cold air sleeve and a fuel gas sleeve, a cooling (or gas return) pipe, and a housing. The flame tube is welded to the air inlet end face of the fuel gas sleeve by means of four support plates. The fuel gas sleeve is bolted to the air distribution plate. The diffuser section is arranged outside the flame tube via a sheath and is bolted to the air distribution plate and the regulating air sleeve. Air enters from the diffuser section, a portion of which enters the combustion chamber for combustion, a portion enters the area between the flame tube and the fuel gas sleeve to mix with the flame at high temperature, and a portion enters the air distribution orifices on the air distribution plate and mixes with the high-temperature, high-speed airflow from the gas return pipe in the cold air sleeve to obtain an airflow suitable for atomization. The injected disinfectant thus forms a mist, which is atomized at the outlet of the device.

[0013] The cooling pipe is concentric with the fuel gas sleeve, which lengthens the fuel gas path and extends the mixing time, but greatly reduces the overall structural length.

[0014] Purpose of the invention

[0015] The object of the present invention is to overcome at least one of the disadvantages of the prior art, particularly in that the exhaust gas leaving the combustion device has not only low NOx levels (e.g., < 10 mg / kWh, preferably < 5 mg / kWh) but also low CO levels (e.g., < 10 mg / kWh).

[0016] More specifically, the object of the present invention is to provide a combustion device that is stable and highly efficient in terms of output, the combustion device being configured to produce combustion (emission) gases compatible with inlet temperatures between 800°C and 1050°C, particularly between 950°C and 1050°C, while keeping NOx and CO levels low, as mentioned above.

[0017] A more particular object of the present invention is the design of a combustion device that can accommodate high λ (excess air) values ​​while allowing flameless combustion. Summary of the Invention

[0018] This invention relates to a combustion device for power generation or combined heat and power (CHP) equipment, the equipment comprising a gas turbine, particularly a micro gas turbine, supplied by the device, the device being suitable for a "flameless" type of combustion state and including:

[0019] - Outer tube;

[0020] - A combustion tube that forms a combustion zone suitable for flameless combustion of a mixture of air and fuel, the combustion tube being concentric with the outer tube and communicating with a fuel injection device and an air injection device arranged at a first end of the combustion tube, referred to as the front end, and the combustion tube being closed at a second end of the combustion tube, referred to as the rear end, the end wall being fixed to the combustion tube and being fluid-tight;

[0021] - The fuel injection device, which includes at least a first orifice referred to as a fuel injection orifice;

[0022] - The air injection device, which includes at least a second orifice referred to as an air injection orifice;

[0023] - A device for discharging combustion gases;

[0024] - A sealing wall that covers the front end of the combustion tube and is connected to the air injection device and the fuel injection device;

[0025] Its features are,

[0026] - The combustion tube is essentially in the form of a cylinder with a single internal volume that allows the gas to recirculate in a flameless combustion state;

[0027] - The combustion gas exhaust device includes at least one opening disposed at the front end of the substantially cylindrical combustion tube, the opening being defined on one end by a cylindrical longitudinal wall of the combustion tube near the closure wall and on the other end by the closure wall, the flow and exhaust of the combustion gases being performed between the longitudinal wall and the outer tube.

[0028] According to an advantageous embodiment of the invention, the combustion device includes one or more of the following technical features in any possible combination:

[0029] - The combustion device further includes a tubular sleeve concentrically arranged between the combustion tube and the outer tube, connected to the closed wall and positioned facing the opening of the discharge device to form an annular region called the reorganization zone, thereby enabling an extension of the residence time of the combustion gases discharged through the opening;

[0030] - The outer tube and the combustion tube at least partially define an annular passage called a bypass, which allows a dilution gas flow that can mix with the combustion gases downstream of the combustion zone to pass through. The enclosed wall includes one or more openings called bypass openings, which are formed in the periphery of the enclosed wall and through which the dilution gas flow enters the bypass.

[0031] - The outer tube and the tubular sleeve at least partially define an annular passage called a bypass, which allows a dilution gas flow that can mix with these combustion gases downstream of the recombination zone to pass through. The closed wall includes one or more openings called bypass openings, which are formed in the periphery of the closed wall and through which the dilution gas flow enters the bypass.

[0032] - The tubular sleeve extends axially upwards for at least 50% of the length of the combustion tube;

[0033] - The combustion device includes a cylindrical pressurization chamber formed by a portion of the outer tube and a sealing wall, the portion being disposed at the front end of the outer tube, and the sealing wall forming the end wall of the pressurization chamber;

[0034] - The pressurization chamber is fluidly connected to the air supply pipe;

[0035] - The opening of the combustion gas exhaust device is an annular opening formed between the closed wall and the front edge of the combustion tube;

[0036] - The fuel injection orifice is centered relative to the combustion tube;

[0037] - The fuel injection device includes an injection head in which the fuel injection orifice is formed;

[0038] - The fuel injection device includes a fuel injection tube, the rear end of which is fixed to the injection head;

[0039] - The air supply duct and the fuel injection pipe are arranged coaxially along a portion of their respective lengths;

[0040] - The air injection port is composed of several ports arranged in the closed wall;

[0041] - The air injection port surrounds the fuel injection port;

[0042] - The air injection device includes an injection ring fixed to the closed wall;

[0043] - The injection ring includes an inner surface that guides the airflow into the combustion zone;

[0044] - The air injection device further includes a guide element disposed at the center of the injection ring;

[0045] - The guiding element includes an outer surface that guides airflow into the combustion zone, a portion of which is substantially conical;

[0046] - The guide element and the injection ring are connected by one or more molding arms;

[0047] - The guide element is aligned with the fuel injection head;

[0048] - The combustion device includes a converging conical tube fixed to the outer tube to discharge combustion gases.

[0049] The present invention also relates to the use of the combustion device described above, characterized in that an airflow is injected into the device at a speed between 60 m / s and 120 m / s in order to obtain a fluid recirculation ratio greater than 1.3 mE / (mA + mF), wherein mE, mA and mF represent the mass flow rates of the gases burned and recirculated in the combustion zone, the mass flow rates of the oxidizing air introduced into the combustion zone (4) and the mass flow rates of the fuel, respectively.

[0050] The present invention also relates to an equipment for power generation or cogeneration of energy, including the combustion device described above.

[0051] Advantageously, the power generation or cogeneration equipment includes a heat exchanger for recovering heat energy from the combustion gases produced in the combustion device in order to preheat the intake air supplied to the combustion device.

[0052] Preferably, the heat exchanger includes a first loop in fluid communication with a section downstream of the turbine, particularly a micro turbine, and a second loop in fluid communication with a section upstream of the combustion device.

[0053] According to the present invention, the λ ratio can reach values ​​as high as 6 to 8, thereby allowing the temperature of the exhaust gases to be sufficiently reduced to be compatible with the turbine inlet. The apparent contradiction with the requirements of flameless combustion is resolved through the optimized geometry of the combustion chamber, which allows for efficient dilution of oxygen in the mixture.

[0054] In general, advantageous embodiments of each subject matter of the invention can also be applied to other subjects of the invention. Where possible, each subject matter of the invention can be combined with other subjects. The subject matter of the invention can also be combined with embodiments described in the specification, and these embodiments can also be combined with each other.

[0055] The features unique to this invention are advantageous within this scope because they enable combustion equipment compatible with various fuels, such as natural gas, biogas, and synthetic gases (syngas, etc.). Furthermore, flameless combustion is stable. Attached Figure Description

[0056] Other features and advantages of the invention will be better understood with the help of the following figures and description.

[0057] Figure 1 An external perspective view of the flameless combustion device according to the present invention is shown.

[0058] Figure 2 A three-dimensional view of a longitudinal section of the flameless combustion device according to the present invention is depicted.

[0059] Figure 3 A three-dimensional view of a transverse cross-section of the flameless combustion device according to the invention is shown, the cross-section passing through the pressurization chamber.

[0060] Figure 4 Two perspective views of the fuel injection port and air injection port of the flameless combustion device according to the present invention are shown.

[0061] Figure 5 This is a schematic depiction of a longitudinal section of the flameless combustion apparatus according to the present invention, wherein flow is indicated by arrows.

[0062] Figure 6 This is a schematic depiction (in a cyclic form) of an energy cogeneration equipment according to the present invention.

[0063] Figure 7 This is a schematic diagram showing the distribution of the temperature field in a longitudinal cross section.

[0064] Figure 8 This is a schematic diagram showing the distribution of the velocity field in a longitudinal section.

[0065] Figure 9 This is a schematic diagram showing the distribution of the CO field in a longitudinal section.

[0066] Figure 10 This is a schematic diagram showing the distribution of the OH field in a longitudinal section. Detailed Implementation

[0067] One embodiment of the combustion device proposed in this invention has been specifically designed to accommodate large λ values ​​while allowing flameless combustion.

[0068] Combustion chamber description

[0069] Figures 1 to 5 An embodiment of a flameless combustion device 100 is shown, which supplies air via an air supply duct of suitable size and shape (typically cylindrical) to a regenerator (105, see below) connected to a turbine (e.g., a micro-turbine). Figure 6 It receives preheated air to reduce pressure drop.

[0070] The air supply duct may include an air delivery duct 21 and an adapter duct 10, which allows the air delivery duct 21 to engage with a first end of the combustion device 100. The adapter duct 10 typically includes at one end a fastening flange 22, particularly a V-shaped flange, for securing the air delivery duct 21 to the adapter duct 10. The adapter duct 10 may have a flange at its other end, referred to as a main flange 23, which can be welded to a connecting pipe. The adapter duct 10 allows access to the interior of the combustion device, such as in… Figure 2 As shown in the document.

[0071] The combustion device 100 can be connected at its other end to the turbine volute (not shown) via a conical tube 24 welded to the outer tube 26 of the combustion chamber 100. A V-shaped fastening flange 25 can provide a connection to the turbine volute.

[0072] As in Figure 2 As shown, the combustion device may include a reinforcement 27 welded to the outer tube 26, the reinforcement 27 ensuring the rigidity of the device 100.

[0073] Figure 2 A combustion device 100 that can be ignited using a heater plug 28 is also shown. The plug 28 passes through the outer tube 26, the tubular sleeve 7, and the combustion tube 5 to access an ideal region for igniting the mixture. This region is preferably located at a distance from the air injection orifice 36, a distance equal to the average diameter defined by the inner surface 31 of the injection ring 40. Furthermore, this region is preferably located at a distance from the central axis of the combustion tube 5, a distance representing approximately ¾ of the average diameter defined by the inner surface 31 of the injection ring 40.

[0074] The combustion device 100 may include a thermocouple 29, preferably of type K, which also penetrates the center of the combustion device 100 to measure the temperature in the combustion zone 4. This thermocouple serves as a safety device to prevent excessively high temperatures inside the combustion tube 5.

[0075] The combustion device 100 includes a fuel injection device comprising a pipe 20 passing through an intake duct 21. This pipe 20 may be fixed, preferably welded, to a fuel injection head 33. This pipe 20 allows fuel to be delivered as far as the injection head 33.

[0076] According to the present invention, a technique is provided for dividing / separating an incoming airflow into two different airflows (a primary flow for combustion and a secondary flow for cooling the mixture). Therefore, Figure 3The combustion device 100 is shown to include a pressurization chamber 1 for dividing the airflow into two streams: a primary stream and a secondary stream. The primary airflow can be injected into the combustion tube 5 via an orifice 36 of an air injection device. The secondary airflow passes through a bypass 6 and mixes with the primary stream downstream. Figure 5 ).

[0077] Bypass 6 allows the secondary flow to pass through the downstream mixing region. Bypass 6 may have openings 39, such as notches, the area of ​​which allows adjustment of the ratio between the primary and secondary flows. Typically, this ratio is equal to 1 in order to obtain a maximum λ of 4 in the combustion zone 4.

[0078] Figure 4 More specifically, a combination of an air injection device and a fuel injection device is shown. In this configuration, the air injection device includes an injection ring 40 having a generally conical inner surface 31. According to this advantageous embodiment, the side of the injection ring 40 facing the combustion tube 5 has a shoulder 34, making it easier to fit the injection ring into the closure wall 14 (e.g., plate) of the combustion tube 5. The fuel injection head 33 may have a conical outer surface 41 extending over a large portion of its length. The fuel injection head 33 may be held at the center of the injection ring 40 by a shaped arm 30 connected to the injection ring 40. The outer surface 41 of the fuel injection head 33 may at least partially define the outer surface of the air injection orifice 36. Shaping the arm 30 allows for a reduction in pressure drop caused by air flowing through the air injection orifice 36. The conical inner surface 31 has an angle that causes the main airflow to converge toward the combustion zone. The angles of the inner surface 31 of the injection ring 40 and the outer surface 41 of the injection head 33 ensure the formation of converging conduits with cross-sections facing the combustion zone 4. The fuel injection tube 20 is welded to the injection head 33 at a recess or shoulder 32 formed in the injection head 33 to ensure a fluid-tight connection. Fuel, preferably gas, is injected from the injection orifice 35. Preferably, the device for combined injection (i.e., combined injection of air and fuel) can be manufactured using an additive 3D printing process (e.g., DMLM, which represents...). Direct metal laser melting It is manufactured using refractory materials (e.g., nickel-based alloys, cobalt-based alloys, or refractory steel). Alternatively, other processes are also possible, such as machining, MIM (Metal Injection Molding), etc. Represents metal injection molding )wait.

[0079] As in Figure 4As shown, air and fuel are injected into the combustion tube 5 through air orifice 36 and fuel orifice 35, respectively. The combustion tube has a cylindrical shape, closed at its ends by end walls 12. For flameless combustion, the gas flow velocity needs to be between 60 m / s and 120 m / s. Combustion gases are discharged from the recirculation zone 4 through one or more openings 9 (e.g., slots). However, a certain proportion of the fluid is recirculated within the combustion zone. Based on the following formula, the recirculation ratio is calculated to be greater than 1.3:

[0080] mE / (mA + mF),

[0081] Where mE, mA, and mF represent the mass flow rates of the gases combusted and recirculated in combustion zone 4, and the mass flow rates of the air and fuel introduced into combustion zone 4, respectively. Clearly, this substantial recirculation of the gases allows for the dilution of oxygen and fuel and induces flameless combustion. The size of opening 9 allows for control of the recirculation level. Metal parts 37, 38 (see...) Figure 2 A component 37, 38 can be used to position the combustion tube 5 within the outer tube 26, while simultaneously fixing the cross-sectional area of ​​the opening 9 (described as slot 9 in this example). One of the components 37, 38 can be welded to the outer tube 26, thus allowing the combustion tube 5 to expand freely.

[0082] The inventors, through first experiments and then numerical verification, realized that adding the sleeve 7 allows for a significant reduction in the CO level in the combustion gases downstream of the combustion device 100, especially when the combustion device 100 also includes a bypass 6. The sleeve 7 is an open pipe concentric with the combustion tube 5. This sleeve 7 prevents excessively rapid mixing between the primary and secondary flows. Therefore, the temperature of the primary flow remains high, and the reaction that reorganizes CO into CO2 can further occur in region 8, known as the reorganization zone. Thus, the CO concentration in the combustion gases can be reduced by approximately 10-fold. Therefore, the length of the sleeve 7 has an impact on CO reorganization and can advantageously be optimized through calculation. In any case, the length of the sleeve is typically at least 50% of the length of the combustion tube 5. Preferably, the sleeve 7 is fixed to the closed wall 14.

[0083] Combustion tube 5 experiences extreme temperatures ranging from approximately 1050°C to 1150°C. Various metallic alloys exist that can be used for the heat treatment of radiant tubes, such as 602CA. ® 310S, Inconel ® 625, and preferably ferritic steel chromium-aluminum alloy Kanthal ® APM. It should be noted that the combustion tube 5 may also have a hemispherical end wall or some other shape of end wall that can improve gas recirculation and pressure drop in the combustion device.

[0084] Other components of the combustion device 100 include, for example, the outer tube 26, the adapter pipe 10, flanges 22 and 23, and the sleeve 7 may be made of steel 310S. Like any other combustion device, this material requires a protective layer that allows for the application of resistance to high-temperature corrosion and oxidation. The combustion tube 5, the outer tube 26, and the sleeve 7 are preferably cylindrical.

[0085] Description of power generation or combined heat and power equipment

[0086] The flameless combustion device 100 can be associated with micro-turbine applications, particularly those aimed at producing electricity or heat using combined heat and power (CHP). Electricity production or CHP equipment may include several modular components (see [link to documentation]). Figure 6 The equipment includes at least a turbine generator and a combustion device 100, which is combined with one or more of the following components: a regenerator 105, a power electronics system (not depicted), a gas-water (or air-water) heat exchanger 103, and an auxiliary unit (not depicted).

[0087] The turbine generator includes a compressor 101, a turbine 104 (e.g., a micro-turbine), and a generator 102, preferably a permanent magnet type, all mounted on the same shaft. Preferably, the shaft bearings may include two radial aerodynamic rolling bearings that do not require lubrication with liquid lubricants such as oil or solid lubricants. Additionally, the turbine generator may include axial aerodynamic rolling bearings designed to compensate for the axial forces between the compressor and turbine pair. The generator 102 may be positioned in front of the compressor 101, suspended beyond the compressor (not depicted). This configuration allows for a highly compact shaft. The electric stator is then fixed to the compressor's volute. The ample space between the generator and the stator ultimately allows the compressor 101 to draw in air.

[0088] The regenerator 105 may include a heat exchanger designed to recover available energy present in the exhaust gas from the turbine 104 to preheat air compressed by the compressor 101, which will be supplied to the combustion device 100.

[0089] The power electronic system (not depicted) can be configured to convert the high-frequency AC current generated by the generator 102 (synchronous AC motor, especially permanent magnet type) into DC current, so that the current can be injected into the grid using an inverter of the type used for solar applications, for example.

[0090] A gas-water (or air-water) heat exchanger 103 can be positioned at the outlet of the cogeneration equipment to recover energy from the exhaust gas in cogeneration mode to heat water or generate steam. Several exchangers can be used. Additionally, each gas-water heat exchanger can be positioned at other locations within the cogeneration equipment that require cooling.

[0091] The auxiliary unit performs the following functions: compressing and regulating the flow of fuel (e.g., gaseous fuel) for injection into the combustion device 100 and the system for water-cooled stator; and possibly for mounting a pneumatic bearing.

[0092] Micro turbines refer to turbines with electrical outputs ranging from 5 kW to 750 kW, preferably from 25 kW to 500 kW. Typically, these turbines are mounted on piston-type internal combustion engines to boost their power.

[0093] Simulation results

[0094] exist Figure 7 , Figure 8 , Figure 9 and Figure 10 The simulation results are presented below. These results were generated using ANSYS 2020 R1 software. The method involves solving the axisymmetric Navier-Stoke (RANS) equations using the assumption of steady-state incompressible flow. Numerical modeling uses a pressure-based incompressible solver equipped with a suitable model for turbulence (e.g., the standard k-ε model, where the first constant C). 1ε Equal to 1.6), radiation model ( Discrete coordinate method A model for the interaction of turbulence and convection-diffusion equations specifically suitable for chemical species undergoing flameless combustion. Vortex dissipation concept and Partial mixing reactor Coupled with PaSR models and reactive gas models (e.g., KEE58, GRI 2.11, etc.). These simulations are run at the end of the grid convergence study, allowing it to be demonstrated that the quality of the results is sufficiently independent of the grid used.

[0095] Temperature field simulation ( Figure 7 The results show that the maximum temperature reached does not exceed 1380°C, which is significantly below the threshold for triggering NOx production. The combustion zone is confined to the closed end of the combustion tube and is quite dispersed, as shown by... Figure 10 As observed, the graph shows the distribution of OH radicals. Furthermore, the extremely high CO concentration in the combustion zone decreases very significantly due to the reorganization of CO into CO2. Figure 9 The predicted emissions for this specific example are:

[0096] NOx = 1.43 ppm;

[0097] CO = 0.50 ppm.

[0098] The test bench was positioned in parallel to measure the performance of the flameless combustion chamber according to the invention. The bench was equipped with a 30 kW electric air heater to preheat the air entering the combustion chamber. Emissions measurements were performed using a Testo 350, enabling measurements of CO (0 ppm to 10,000 ppm) and NO (0 ppm to 4,000 ppm). Air flow rate was measured using a GasView volumetric flow meter manufactured to have an accuracy of ±3% at full scale. The gas flow rate was adjusted using an Elflow-type flow controller with a full-scale accuracy of ±0.5%. Key measurements are summarized in Table 1.

[0099]

[0100] Table 1: Emission Measurement Values

[0101] (1) Air flow rate 25 g / s, air temperature 650°C

[0102] (2) Gases tested according to EN 437

[0103] List of reference numerals

[0104]

[0105]

[0106]

Claims

1. A combustion device (100) for power generation or cogeneration equipment, said equipment comprising a gas turbine supplied by said device, said device being adapted for a "flameless" type of combustion state and comprising: -Outer tube (26); - Combustion tube (5), which forms a combustion zone (4) suitable for flameless combustion of a mixture of air and fuel, the combustion tube (5) being concentric with the outer tube (26) and communicating with a fuel injection device and an air injection device, which are arranged at a first end of the combustion tube (5) referred to as the front end, and the combustion tube (5) being closed at a second end of the combustion tube (5) referred to as the rear end by an end wall (12), which is fixed to the combustion tube (5) and is fluid-tight; -The fuel injection device includes at least a first orifice (35) referred to as the fuel injection orifice. - The air injection device includes at least a second orifice (36) referred to as the air injection orifice. - A device for discharging combustion gases; - A sealing wall (14) that covers the front end of the combustion tube (5) and is connected to the air injection device and the fuel injection device; in: - The combustion tube (5) is basically in the form of a cylinder with a single internal volume that allows the gas to be recirculated in a flameless combustion state; - The combustion gas exhaust device includes at least one opening (9) arranged at the front end of the substantially cylindrical combustion tube (5), the opening (9) being defined on one hand by one end of the combustion tube (5) near the cylindrical longitudinal wall of the closure wall (14) and on the other hand by the closure wall (14), the flow and exhaust of the combustion gases being performed between the longitudinal wall and the outer tube (26); The combustion device (100) is characterized in that it further includes a tubular sleeve (7) concentrically arranged between the combustion tube (5) and the outer tube (26), connected to the closed wall (14) and positioned facing the opening (9) of the discharge device to form an annular region called the recombination region (8), thereby enabling an extension of the residence time of the combustion gases discharged through the opening (9).

2. The combustion device (100) as described in claim 1, characterized in that, The outer tube (26) and the combustion tube (5) at least partially define an annular passage called a bypass (6), which allows a dilution gas flow that can mix with the combustion gases downstream of the combustion zone (4) to pass through. The enclosed wall (14) includes one or more openings (39) called bypass openings, which are formed in the periphery of the enclosed wall and through which the dilution gas flow enters the bypass (6).

3. The combustion device (100) as described in claim 1, characterized in that, The outer tube (26) and the tubular sleeve (7) at least partially define an annular passage called a bypass (6), which allows a dilution gas flow that can mix with these combustion gases downstream of the recombination zone (8) to pass through. The closed wall (14) includes one or more openings (39) called bypass openings, which are formed in the periphery of the closed wall and through which the dilution gas flow enters the bypass (6).

4. The combustion device (100) as described in claim 1, characterized in that, The tubular sleeve (7) extends axially over at least 50% of the length of the combustion tube (5).

5. The combustion device (100) according to any one of claims 1 to 4, comprising a cylindrical pressurization chamber (1) formed by a portion of the outer tube (26) and a sealing wall (14) arranged at the front end of the outer tube (26), the sealing wall (14) forming the end wall of the pressurization chamber (1).

6. The combustion device (100) as described in claim 5, characterized in that, The pressurization chamber (1) is fluidly connected to the air supply pipes (10, 21).

7. The combustion device (100) as described in any one of claims 1 to 4, characterized in that, The opening (9) of the combustion gas exhaust device is an annular opening formed between the closed wall (14) and the front edge of the combustion tube (5).

8. The combustion device (100) as described in any one of claims 1 to 4, characterized in that, The first orifice (35) is an orifice centered relative to the combustion tube (5).

9. The combustion device (100) as described in any one of claims 1 to 4, characterized in that, The fuel injection device includes an injection head (33) in which the first orifice (35) is formed.

10. The combustion device (100) as described in claim 6, characterized in that, The fuel injection device includes an injection head (33) in which the first orifice (35) is formed.

11. The combustion device (100) as claimed in claim 10, characterized in that, The fuel injection device includes a fuel injection tube (20) with its rear end fixed to the injection head (33).

12. The combustion device (100) as described in claim 11, characterized in that, The air supply pipe (10, 21) and the fuel injection pipe (20) are arranged coaxially over a portion of their respective lengths.

13. The combustion device (100) as described in any one of claims 1 to 4, characterized in that, The second orifice (36) is composed of several orifices arranged in the closed wall (14).

14. The combustion device (100) as described in any one of claims 1 to 4, characterized in that, The second opening (36) surrounds the first opening (35).

15. The combustion device (100) as described in claim 9, characterized in that, The air injection device includes an injection ring (40) fixed to the closed wall (14).

16. The combustion device (100) as claimed in claim 15, characterized in that, The injection ring (40) includes an inner surface (31) that guides the airflow into the combustion zone (4).

17. The combustion device (100) as described in claim 15 or 16, characterized in that, The air injection device further includes a guide element disposed at the center of the injection ring (40).

18. The combustion device (100) as claimed in claim 17, characterized in that, The guiding element includes an outer surface (41) that guides the airflow into the combustion zone (4), a portion of which is substantially conical.

19. The combustion device (100) as claimed in claim 17, characterized in that, The guide element and the injection ring (40) are connected by one or more molding arms (30).

20. The combustion device (100) as claimed in claim 17, characterized in that, The guiding element is consistent with the injection head (33).

21. The combustion device (100) according to any one of claims 1 to 4, comprising a converging conical tube (24) fixed to the outer tube (26) to discharge combustion gases.

22. The combustion device (100) as claimed in any one of claims 1 to 4, wherein, The gas turbine is a micro gas turbine.

23. Use of the combustion device (100) as described in any one of claims 1 to 22, characterized in that, The gas flow is injected into the device at a speed between 60 m / s and 120 m / s in order to obtain a fluid recirculation ratio greater than 1.3, mE / (mA + mF), where mE, mA and mF represent the mass flow rates of the gas burned and recirculated in the combustion zone, the mass flow rates of the oxidizing air introduced into the combustion zone (4) and the mass flow rates of the fuel, respectively.

24. An equipment for power generation or cogeneration of energy, comprising a combustion device (100) as described in any one of claims 1 to 22.

25. The power generation or cogeneration equipment as claimed in claim 24, comprising a heat exchanger (105) for recovering heat energy from combustion gases produced in the combustion device (100) in order to preheat the intake air supplied to the combustion device (100).

26. The power generation or cogeneration equipment as described in claim 25, characterized in that, The heat exchanger (105) includes a first loop in fluid communication with a section downstream of the turbine (104) and a second loop in fluid communication with a section upstream of the combustion device (100).

27. The power generation or combined heat and power equipment as described in claim 24, wherein, The turbine is a micro turbine.

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